Experimental Composition of Two Systems: Ring Resonator Structures and Y-shaped Demultiplexer

Abstract

In this work, we experimentally investigated two acoustic systems: the Yshaped demultiplexer and the acoustic ring resonator. The first experiment was a demultiplexer which separates and transmits specific frequencies from a broadband input signal. The acoustic demultiplexer investigated here is based on resonances created by side-attached waveguide stubs. The Y-shaped waveguide sent broad bandwidth sound along an input line. Two output lines with a stub filter arrangement transmitted narrow bands of two different frequencies separated from the broadband input. The second set of experiments concerned ring resonators which are widely used in optics as filters and switches. Here we investigated the acoustic analog to the optical ring resonator. Three specific ring resonators systems are demonstrated: a simple single ring structure that acts as a comb filter, a single ring between two parallel waveguides that acts as an add-drop filter, and a sequential array of equally spaced rings that creates acoustic band gaps. The acoustic ring resonators consist of a circular waveguide attached tangential to a straight waveguide. The ring waveguide has resonances whenever the path around the ring equals an odd half-integer multiple of the wavelength. We showed that this phenomenon can be used to create notch filters, adddrop filters, and broad acoustic bandgap reflectors. The experiments are conducted in linear waveguides using an impulse response method. The ring resonators were created via 3D printing. Finite-element numerical simulations were conducted using COMSOL Multiphysics software. The experimental results were in good agreement with numerical models rendered in python and finite-element simulations.